#pragma comment(linker, "/STACK:10000000")
#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <set>
#include <map>
#include <cstdio>
#include <cassert>
#include <string>
#include <cstring>
#define ldb long double
#define ll long long
#define fi first
#define se second
#define fill(a, c) memset(a, c, sizeof(a))
#define sqr(a) ((a) * (a))
#define nextLine() {int c = 0; while((c = getchar()) != 10 && c != EOF);}
#define getBit(mask, k) (((mask) / pw[k]) % pw[1])
#define setBit(mask, k, l) (((mask) / pw[k + 1] * pw[1] + (l)) * pw[k] + ((mask) % pw[k]))
#define debug(a) cerr << #a << " = " << a << " ";
#define debugl(a) cerr << #a << " = " << a << "\n";
#define mp(a, b) make_pair(a, b)
#define pb(a) push_back(a)
#define ff first
#define ss second 
const ldb LDINF = 9128739847123.00;
const ldb eps = 1e-9;
const int inf = 1 << 28;
const ldb pi = fabsl(atan2l(0.0, -1.0));
using namespace std;


int N, K;
int x[1232];
int a[1232];

void load()
{
	cin >> N >> K;
	memset(a, 0, sizeof a);
	for (int i = 0; i < N; i++)
	{
		scanf("%d", &x[i]);
		a[x[i]] = 1;
	}
}

void solve()
{
	int res = 0;
	int last;
	for (last = 1000; a[last] == 0 && last > 0; last--);
	int size = 0;
	while (a[last] == a[last - size])
		size++;
	while (last - size > 0)
	{
		a[last] = 0;
		a[last - size] = 1;
		res += size / K;
		if (size % K != 0) res++;
		last--;
		while (last - size > 0 && a[last] == a[last - size]) size++;
	}
	cout << res << "\n";
}

#define file "coins"
int main()
{
	#ifndef ONLINE_JUDGE
		freopen(file".in", "rt", stdin);
		freopen(file".out", "wt", stdout);
	#endif
	int T;
	cin >> T;
	for (int i = 0; i < T; i++)
	{
		load();
		solve();
	}
	return 0;
}
